Brummel
8860600e37
Add `(let-rec NAME (params ...) (type ...) (body ...) (in ...))` as a form-A surface and a `Term::LetRec` AST variant. The 16a desugar pass lifts each LetRec whose body has no captures from the enclosing scope to a synthetic top-level fn `<hint>$lr_N` and substitutes the original name; typecheck and codegen never see LetRec. Capture detection panics at desugar time, queued for 16b.2. Tests: 95 → 99 (+1 e2e local_rec_factorial_demo, +2 desugar unit, +1 parse unit). The new fixture `examples/local_rec_demo` runs `fact` at n=1, 3, 5 → prints 1, 6, 120. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
27 lines
1.0 KiB
Plaintext
27 lines
1.0 KiB
Plaintext
; Iter 16b.1 — first consumer of (let-rec ...). A single-fn helper
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; `fact` is bound by a local recursive let inside `main`'s body and
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; called at three different inputs. The desugarer lifts `fact` to a
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; synthetic top-level fn (because the body has no captures from
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; `main`'s scope) and substitutes the references. The lifted fn is
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; type-checked and codegen'd identically to a hand-written
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; top-level def. Output (per line): 1, 6, 120.
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(module local_rec_demo
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(fn main
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(doc "Iter 16b.1: drive a let-rec'd factorial helper at three inputs. Expected stdout (per line): 1, 6, 120.")
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(type (fn-type (params) (ret (con Unit)) (effects IO)))
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(params)
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(body
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(let-rec fact
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(params n)
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(type (fn-type (params (con Int)) (ret (con Int))))
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(body
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(if (app <= n 1)
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1
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(app * n (app fact (app - n 1)))))
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(in
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(seq (do io/print_int (app fact 1))
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(seq (do io/print_int (app fact 3))
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(do io/print_int (app fact 5)))))))))
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